How about a tweak option for subtler scrollbars?

[Martinique]

Colorful scrollbars are distracting, especially in IDEs and such applications that have many. Gray would suit them better, as they're not important elements demanding attention. The pre-Unity Ambiance theme looked pretty balanced, with only the most important items having color.

Having a gray option for selections would be useful, too. I like the orange theme, but selecting big chunks of text burns my eyes.

The actual shade of gray could be calculated from the color value. With the luminosity method contrast remains similar, so the black-selected-text tweak would be compatible. Not sure if colors like yellow would leave the contrast too low, though.